Mixing and delivering apparatus



May 9, 1961 R. J. UNLAND ETALY 2,983,439

MIXING AND DELIVERING APPARATUS 5 Sheets-Sheet 1 Filed May 9, 1958 INVENTORS.

May 9, 1961 R. J. UNLAND ET AL 2,983,489

MIXING AND DELIVERING APPARATUS Filed May 9. 1958 5 Sheets-Sheet 2 INVENT RS.

y 1961 R. J. UNLAND ET AL 2,983,489

MIXING AND DELIVERING APPARATUS Filed May 9, 1958 5 Sheets-Sheet 5 May 9, 1961 R. J. UNLAND ET AL 2,983,489

MIXING AND DELIVERING APPARATUS Filed May 9, 1958 5 Sheets-Sheet 4 May 9, 1961 R. J. UNLAND ET AL 2,983,489

MIXING AND DELIVERING APPARATUS Filed May 9, 1958 5 Sheets-Sheet 5 "I D (D g n m w- .J "3 1 :5 4|

l- 1 k J INVENTORS.

AIR

81 PP LY J. Unland, 1916 Road, and Roy R. Patcllen,

3742 Ardley Ave., both of Oakland, Calif.

Filed May 9, 1958, Ser. No. 734,164

4 Claims. (Cl. 259-3) Roger The present invention relates to an improved mixing device together with advanced means for delivering mixed material from the device.

Although innumerableimixing devices and systems have been developed, they are conventionally limited to batch mixing wherein a single load of material is mixed during a mixing cycle and mixed material is thus made available only periodically. The present invention employs a continuous mixing cycle and thus continuously delivers mixed material so that delays in delivery are entirely precluded. Also the mixing process of the present invention is very short, a matter of a few seconds, in'that a highly advantageous mixing action is achieved and thus material rapidly moves through the mixer to shortly change from unmixed to final mixed condition whereby rapid start up is attained and also the disadvantages of bulky equipment and large batch mixing are obviated.

While the present invention is widely applicable in the field of mixing and delivery, being capable of construction in any size from that of a kitchen utensil. to that of the largest construction equipment. there is herein chosen as an example the utilization of the invention as a concrete mixer without intending any limitation thereby. In the mixing of concrete a plurality of dry materials are mixed with water to form a sort of relatively dry slurry and it has been found that the proportion of water in this slurry bears directly upon the strength of the resultant concrete. More particularly, a relatively dry mix is most highly desired, for the presence of any excess water beyond that required to set up the concrete only evaporates eventually to form voids or honeycombs. Also, the size of aggregate employed is of importance, for

a substantial aggregate size greater than that normally used materially increases the strength of the concrete. Contrary to conventional concrete mixing devices and systems, the present invention is adapted to mix material including quite large aggregate and to deliver same under pressure as by a hose and nozzle. Also the present invention operates to mix the dry materials and water thoroughly prior to delivery or transport of same as through a hose. This is highly advantageous in that the mixture of wet and dry ingredients much morereadily traverses pipes or hoses without undue resistance to flow, as compared to the transport of dry mix alone. I

The present invention is further advantageous in employing only relatively simple, inexpensive components to thereby minimize the cost of manufacture and the problems of maintenance. For example, the mixing portion of the invention utilizes a rotating drum with a smooth drum interior, as contrasted to more conventional mixers. Along with the aforementioned advantages is included the elimination of pressure chambers in the invention with the preclusion thereby of the high cost and possible hazards of same.

Together with the above, the present invention includes a novel and highly improved control system operating with both the mixing and delivery portions to provide the control necessary for attaining an exact mix- 2383,48!) Patented May 9, 1951 ice ture proportion to the endof maximizing strength of the resultant concrete and minimization of the cost thereof at the same time. In the present invention, a single control is provided in convenient location at the point of delivery and operating to immediately vary the mixture deliveryand also to automatically insure cleaning of the entire system upon shutdown. Material flow and delivery is controlled without the use of valving in the delivery or flow line so that a completely unimpeded mixed material flow is achieved whereby larger sized material constituents may be incorporated and the problems of flow valving maintenance are precluded.

More specifically to the control herein, there is utilized an air system adapted for ready control at the delivery nozzle to control the material supply, mixing, and delivery. Both dry material and water are fed to the mixing portion of the invention under the dictates of this air control system and likewise the mixed material delivery, when a pressure delivery system is employed, is directly controlled by the air system.

It is an object of the present system to provide a continuous delivery rotating drum mixer.

It is another object of'the present invention to provide a high speed continuous mixingdevice of simplified structure.

It is a further object of the present invention to provide mixing and delivery apparatus with continuous dry mix feed thereto and employing a high speed rotating open drum.

It is yet another object of the present invention to provide improved material delivery means wherein a surrounding air jet ejects a central stream of material.

Another object of the present invention is to provide improved control means for mixing and delivery of materials including nov valving in the delivery system.

A still further object of the present invention is to provide in a rotating drum continuous mixing device control means providing automatic drum cleansing upon shut off.

While there are numerous other objects that could be herein listed as well as further advantages of the invention that could be explained, it is believed that same will be apparent from the following description of the invention taken together with the accompanying drawings of a single preferred embodiment of the invention with certain identified modifications and wherein:

Figure l is a sectional view of the invention taken on a vertical central plane;

Figure 2 is a transverse sectional view taken at 22 of Figure 1;

of Figure 1;

Figure 4 is .a plan view of the invention;

Figures 5 and 6" are central sectional views taken vertically and horizontally, respectively, through the outlet end of the mixing apparatus and showing alternate construction thereof; and p Figure 7 is a layout of the flow system of theinvention.

Considering now the structural details of the present invention and referring first to the mixing and measuring portions of the present invention, there will be seen from Fig. 1 to be provided a cylindrical mixing drum 11 mounted for rotation about the axis thereof in a pair of large bearings 12 and 13 that are, in turn, mounted upon a base plate 14. High speed drum rotation is accomplished by a motor 16 mounted on the base 14 and having a rotary shaft 17 extending therefrom. Transmission of rotary motion to the drum 11 from the motor 16 is accomplished 'by one or more V-belts 18 fitted about pulley wheels 19 fixed to the drum and about pulley Wheels 21 fixed to the motor shaft 17.

The drum 11 is adapted to receive dry and liquid ingredients for intimate mixing thereof and the dry ingredients are fed from a hopper 22 mounted by a I'lgld vertical frame 23 upon the base 14 near the inlet end of the drum 11. Actual delivery of the dry ingredients to the drum from the hopper is accomplished by means of a wide belt 24 extending over a pair of rollers 25 and 26 mounted for rotation upon the frame. The second or drive roller 26 has a shaft 27 therethrough carrying a pulley wheel 28 and a belt 29 thereon extends, downward about a pulley wheel 31 mounted upon a shaft 32 of a feed motor 33 secured to the base 14. The other roller 25 operates only as an idler and with the belt 24 secured about these rollers, the belt is turned to travel beneath the hopper toward the drum.

As to storage and metering of the dry ingredients, reference is made to Fig. 2 wherein it will be seen that the hopper 22 is divided into a plurality of generally vertical compartments each adapted to contain a different material, as for example, sand, cement, and aggregate. The hopper has a closed bottom and open top and may taper outward from a dimension less than the belt width, for maximized hopper capacity, as shown in Fig. 2. The belt 24 is closely spaced beneath the hopper and metering of materials from the hopper is carried out by the provision of vertically sliding gates 34 disposed over vertically elongated openings 36 in the side of the hopper toward the drum. Each of the hopper compartments has an opening 36 therein extending from the bottom thereof upward and each of the openings is covered by one of the vertically sliding doors or gates 34 with locking means 37 extending through slots in the gates for fixing same in predetermined position. It will be appreciated that with a constant belt velocity and adequate material in the hopper, a cone of material will pile up on the belt depending upon the gate opening. The amount of material moved by the belt is proportional to the size of the base of the aforesaid cone and this cone size is dependent upon the gate opening, i.e., the height to which the gate is opened. Thus it will be seen that the dry ingredients within the hopper are easily individually metered therefrom by adjustment of the position of the separate gates on the compartments thereof.

Provision is made for supplying the drum with dry ingredients carried by the belt from the hopper and a scoop 38 may be provided for this purpose. This scoop 38 is formed as an inclined tapered cylinder having the small end thereof extending downward into the inlet end of the drum and the large end flattened on the undersu'rface to touch the belt across the width thereof at the drive roller 27. As the belt 24 moves toward the drum beneath the hopper it carries dry ingredients from the hopper,

and the scoop 38 scrapes them from the belt so that they slide down the scoop into the drum. A flexible annular end wall 39 is secured as by bolts 41 to the drum 11 about the scoop and out of contact therewith so as to prevent the spilling of materials in the drum from the end thereof.

In addition to the dry ingredients supplied to the drum in the above-described manner, there is additionally supplied to the drum liquid ingredients such as water, where, for example, concrete is being mixed in the drum. Considering that the liquid ingredient is water, there is provided a pump 42 having an inlet adapted for connection to a supply of Water and driven by the feed motor 33, as through a pulley belt 43. The pump outlet is connected to a pipe 44 that extends through a valve 45 to the center of the outlet end of the drum and into the drum thereat, terminating in a nozzle, or head 46 directed axially of the drum and adapted to project a fine spray of water lengthwise of the drum. The nozzle 46 which extends into the drum preferably does not itself contact the drum or the closed outlet end thereof in the instance Where the outlet end of the drum rotates, as noted in more detail below.

Mixing of material, such as concrete, within the drum 11 is accomplished by high speed drum rotation fromthe drum motor 16. The drum is rotated at a speed that is at least suflicient to hold the materials to be mixed against the drum walls by centrifugal force. Within the drum 11 there is provided a scraper blade 47 that is generally arcuate cross section, extending generally longitudinally thereof and disposed in scraping contact with the interior drum surface along the top thereof, as best seen in Fig. 3. Upon the blade 47 are mounted a plurality of vanes 48 spaced along the blade length and disposed generally transversely thereof on the side ofthe blade toward which the drum rotates. These vanes are slanted slightly toward the outlet end of the drum from the blade edge and operate to direct material scraped from the drum by the blade generally toward the outlet end of the drum. Mounting of the blade 47 may be accomplished from a single end of the drum as by connection of the blade to an end plate 49 at the outlet end of the drum and a support bar 51 also attached thereto and to the blade.

Various configurations of the outlet end of the drum are possible, it being required that stationary mounting for the blade be provided and that the drum be freely rotatable. Also, provision is made at the outlet end of the drum for discharging material mixed within the drum. One end embodiment is illustrated in Fig. 1 wherein an annulus 52 with an open inner side is secured to the stationary end plate 49 and disposed in overlaying relation, the drum end to seal same and yet allow rotation thereof. This end plate 49 is either directly or indirectly fixed to the base plate 14 and in the above-described embodiment, a plurality of paddles 53 are atfixed about the drum end extending therefrom both longitudinally and radially to fit within the annulus 52 and to move thereabout with drum rotation. Suitable egress means are provided for removing materials mixed in the drum 11 and same may most simply include but an aperture in the annulus 52 adjacent the bottom thereof, communicating, for example, through a pipe or tube, not shown, to such as concrete forms. In this instance, the rotating paddles 53 operate to push the mixed material out the egress aperture.

Other egress means may also be provided and likewise, alternative end structures may be employed. Thus in Figs. 5 and 6, the end plate 49 is employed with a grooved edge to accommodate the drum end without provision for paddles or the like to move the mixed material, as in many applications of the invention, even including relatively dry concrete mix, a suitable flow of material is achieved merely by blade and vane action. As regards the delivery of mixed materials from the drum, provision may be made for forced flow, as shown in Fig. 3. There is therein provided an eductor 56 including-a central pipe 57 connected to an outlet pipe 58 that communicates with the drum discharge end through the bottom of the annulus 52 by extension tangentially therefrom in the direction of drum travel. About this inner eductor pipe there is attached a housing or cover 59 forming a high pressure air chamber 61 and terminating in an outlet pipe 62 extending beyond the central pipe 57 radially outward therefrom to form a restricted passage. The eductor cover 59 extending beyond the central eductor pipe 57, an outlet pipe or cylinder 62 is adapted for airtight connection with such as a flexible delivery hose 63 for carrying mixed material to a site of deposit or use. With the paddles 53 rotating within the annulus 52, the material reaching the discharge end of the drum is pushed into the discharge pipe 58 and thence into the eductor pipe 57. High pressure air provided to the chamber 61 by means later described escapes at high velocity through the outlet pipe 62 about the central eductor pipe 57 toward the hose 63 to pick up or entrain the mixed material in the central eductor pipe 57 and force same at high flow rates along the'hose 63.

In the instance wherein the discharge end of the drum is modified as shown in Figs. 5 and 6, there is provided a somewhat different eductor attachment in that the discharge pipe 58 is disposed at an angle to the drum axis through the end plate 49 and a deflecting plate 64 is disposed partially across the bottom of the drum fitting the curvature thereof and aligned with the discharge pipe. The drum blade 47 is in part foreshortened in this embodiment to terminate short of the end plate in the main so as not to strike the deflecting plate angled across the bottom of the drum at the discharge end thereof. With this structure, the discharge end structure is simplified, and the component of motion of the mixed material longitudinally of the drum, as imparted by the blade vanes, is sufiicient to cause the mixed material to move into the area of the deflecting plate 64 whereat same is channelled into the eductor. it has been further determined that for many applications of the invention substantially no end plate is required, for with proper adjustment of parameters all the mixed material reaching the discharge end of the drum strikes the deflecting plate to move into the eductor. It is further to be appreciated that the eductor in operation produces a sucking action, by virtue of the directed air fiow therethrough, which action serves to draw materials into the eductor inlet as well as to force them out the discharge end thereof. Thus for many applications, the outlet end structure may be even further modified to exclude the end plate as such with only blade mounting means being located thereat and in these instances all problems of providing a rotary joinder of drum and end plate are obviated. I

In addition to the actual mixing of materials, the present invention includes provision for controlling not only the mixing but also the delivery of the mixed material. In this respect, reference is made to Fig. 7 illustrating a preferred delivery and control system and showing as a block '71 the above-described mixing structure including material supply means. The eductor 56 is shown connected to the fiexible delivery hose 63 which terminates at a delivery nozzle 72 including, in addition to a central opening or passage 73 therethrough, at least one handle 74 for manual grasping of the nozzle.

Air is supplied to the eductor 56 from an air supply 76 including, for example, a conventional compressor and tank with suitable regulating means for maintaining a constant output pressure. Air from the supply 76 is directed through a gate valve 77 into a main regulator valve 78 and thence through a main air line 79 to the eductor housing 59.

Control of the mixing and delivery is herein accomplished with the air system and to this end there is provided an auxiliary air line 81 connected to the main air line intermediate the gate valve 77 and regulator valve 78. A pressure reducing valve 32 is connected in the auxiliary air line 81 and a control valve 83 forms'the outlet end of the auxiliary line. This control valve 83 may be most conveniently disposed at the nozzle 72, as for example, in a passage through a handle 74 thereof. The control valve 83 is spring loaded to'remain normally closed and is only open during manual. depression of the stem extending through the nozzle handle 74.

Control of main air flow to the eductor 56 is accomplished in the main regulator valve 7 8 which includes a valve head 84 mounted upon a flexible diaphragm 86 and spring loaded to normally unseat and provide air passage through the valve. Connection is made through a pressure reducing and needle valve 7 from the auxiliary air line 81 to the main regulator valve 78 into a chamber 88 having the flexible diaphragm 86 forming a wall thereof so that auxiliary line air pressure urges the main regulator valve 78 closed against the pressure of the spring loading. With the control valve 83 at the nozzle closed, the auxiliary line 31 contains air at suflicient pressure to pressurize the main regulator valve chamber 88 and close the valve so that no air reaches the eductor 56. Opening of the valve 83 to the atmosphere releases the auxiliary line pressure and thus allows the main regulator valve 73 to open and deliver air to the eductor.

In addition to the foregoing control, therev is provided a conventional pressure controlled rheostat 89 connected in circuit between input terminals 91 and the motor 33. The input terminals 91 are adapted for connection across asuitable electrical power supply (not shown) and one of the terminals is directly connected to the motor while the other is connected to the motor through the rheostat 89 with the latter having an ofi position electrically opening the circuit. The pressure portion of the rheostat is connected through an adjustable pressure reducing valve 92 to the auxiliary airline 81 so that with maximum pressure in the line the rheostat is turned to the off position and with decreasing auxiliary line air pressure moves to dispose a decreasing resistance in the motor circuit whereby the motor operates at increasing speed.

A further control provided from the auxiliary air line 81 is that of water flow to the mixing drum and same is accomplished by connecting the water regulating valve 45 to the auxiliary air line 81 through an adjustable pressure reducing valve 93. This control is set to close the water regulator valve at maximum auxiliary line pressure and to progressively open the former with decreasing pressure inthe auxiliary line. V 7

Particular advantage is attained by theabo've-described control system and in connection therewith note that the drum drive motor 16 is directly connected across the power input terminals 91 through a switch 94. By appropriate setting of the reducing valves '87, 92 and 93 connected to the auxiliary air line 81 a desired sequence of operation of the invention is provided. The main regulator valve 78 is set to operate at the highest pressure through the valve 87, i.e., reduction of pressure in the auxiliary line 81 by opening of the valve '83, first afiects the main regulator valve to open same and deliver air to the eductor 56. As the auxiliary linepressure co-ntinues to decrease, the rheostat 89 and water regulator valve 45 are affected so that the feed motor 33 is energized and water is sprayed into the drum. By providing the motor switch 94 ahead of both feed motor 3-3 and drive motor 16, as illustrated, protection is afforded against feeding material into a stationary drum. Of course fail safe features may be incorporated in the circuitry, as for example, an electrical switch in the feed motor circuit responsive to water flow and drum rotation so as to de-energize the feed motor upon failure of either. The foregoing control settings are particularly advantageous in shut down or momentary interruption of mixed material delivery for upon increasing the pressure of the auxiliary air line by closing the valve '83- at the nozzle the feed motor and water flow are first stopped with air continuing to flow through the eductor for a short period thereafter to automatically clean the system and in particular the hose 63 of the mixed material.

Insofar as the overall operation of the invention is concerned, same followsdirectly from the foregoing description of the individual components. Thus, in brief, the hopper 22 is firstfilled with separate materials to be mixed and the gates 34 are opened to relatively adjusted heights and locked in position. The main switch 94 is closed to energize the drive motor 16 which then rotates the drum 11 at a relatively high speed, say 600 r.p.m., in the bearings 12' and 13. The operator at the nozzle 72 then directs the latter at the point where mixed material is to be delivered and depresses the stem of the valve 83 to open same. With the air supply maintaining a predetermined outlet pressure the main air line has previously been closed by the main regulator valve 78 and likewise the feed motor 33 has been shut off at the rheostat and the water valve 45 closed, all by the auxiliary line air pressure. Reduction of this pressure by opening of the line to the atmosphere at the valve 83 first causes the main regulator valve to open and deliver air to the eductor whereby air flows through the hose 63 and out the nozzle 72 to clear same. Further reduction of the auxiliary line pressure lowers the pressure at the rheostat 89 so that same moves to place a reduced resistance in the feed motor circuit and this motor then operates at a slow speed. Simultaneously, the water regulator valve opens slightly in response to the reduced auxiliary line pressure. The feed belt 24 is moved by the feed motor to deliver material to the rotating drum 11 through the scoop 38. Within the rapidly rotating drum the entering material is carried up the drum sides and scraped from the drum top by the blade 47 with the vanes 48 thereof directing the falling material slightly toward the outlet end of the drum. As the material is scraped from the drum surface it falls through a spray of liquid such as water directed axially of the drum from the liquid nozzle 46. The velocity of drum rotation is sufiicient to impart to the material within the drum a centrifugal force in excess of gravity so that the material clings to the interior drum surface until scraped therefrom by the blade 47 whereupon it falls to the bottom of the drum through the water spray. Each time the material falls from the drum owing to the scraper it moves longitudinally of the drum under influence of the vanes 48 and the material repeats this cycle a very large number of times in moving to the discharge end of the drum and tumbles during each fall so as to become intimately mixed not only among the various dry constituents but also with the liquid sprayed thereon.

The consequence of the foregoing is the arrival at the discharge end of the drum of a steady flow of thoroughly mixed material which is then directed into the outlet pipe 58, either by means such as the rotating paddles 53 or by the deflecting plate 64 scraping the material from the rotating drum so that the material moves by its own impetus into the outlet pipe 58. Air flows from the main air line 79 into the eductor housing chamber 61 and thence about the central eductor pipe 57 into the eductor outlet pipe 62 to therein entrain mixed material from the outlet pipe 58 via the central eductor pipe 57. The air and mixed material is forced by air pressure through the flexible hose 63 to spray from the nozzle 72 in quantity proportional to the opening of the control valve 83 in the auxiliary air line 81 at the nozzle.

It will be appreciated that precise control of the flow of material is provided in the present invention without the inclusion of any valving or other obstructions in the fiow system of mixed material so that an optimized material flow is attained as well as maximum dependability and minimum maintenance and repair. Furthermore, the mixed material delivery system is entirely free of constricted or obstructed passages so that materials having substantial individual size may be mixed and delivered without clogging of the system. This is of particular importance in many applications and, for example, in the mixing of concrete, large sized aggregate may be included, which reduces the cost of the mix and materially enhances the strength of the resultant concrete. Also, in the same vein, the unconstn'cted delivery system allows delivery of a relatively dry mixture and this also materially enhances the resultant strength of the concrete, for the inclusion of water beyond the amount required for promoting chemical action between the dry constituents serves only to cause eventual voids and honey-combing brought about by evaporation of the excess water.

Cessation of material delivery through the nozzle 72 is readily accomplished by the operator merely by releasing the valve 83 to close same. This raises the pressure in the auxiliary air line 81 and immediately causes the rheostat 89 to move to off position whereby the feed motor 33 is de-energized to stop the belt 24. No more dry ingredients are fed into the rotating drum and also the water regulator valve 45 is closed by the reduced auxiliary air pressure so that the water delivery to the drum is halted. The drum continues to rotate so that no material can be left therein and also the main air to the ejector 56 continues for a short time following cutoff of the feed motor and Water to blow out the hose 63 and eductor for thoroughly cleansing same. The main regulator valve 78 closes at a somewhat higher auxiliary air pressure, thus following in time de-activation of the feed motor and shutofi of the water flow, so that the invention is then ready for repeated use.

What we claim is:

1. In a mixing and delivery apparatus having a cylindrical drum rotated at high speed about the longitudinal axis thereof by a motor, continuous feed means driven by a motor and providing a continuous controllable supply of proportioned materials to said drum for mixing therein, fixed scraping means extending into said drum in scraping relation thereto for tumbling materials therein for intimate mixing, and an eductor means for delivering mixed materials from said drum in combination with a controllable spray means for spraying a liquid in a controlled flow counter-currently to the travel of materials through said drum, control means comprising a main air system to said eductor for entraining mixed material therein and delivering same from the eductor, an auxiliary air pressure ssytem of variable pressure and including a control valve for varying the presusre, a main regulator valve in said main air system controlled from said auxiliary air system, a pressure responsive rheostat connected in circuit with the motor driving said feed means and connected to said auxiliary air system for control therefrom, and a liquid regulator valve connected to said spray means and to said auxiliary air system for control by the latter whereby said control valve in the auxiliary air system controls the amount of material fed to. said drum and liquid sprayed therein as well as the delivery of material from said drum.

2. Mixing and delivery apparatus comprising a drum adapted for high speed rotation and having a scraper blade disposed in scraping relation to the top of the drum interiorly thereof, an endless belt driven at a variable speed by a feed motor to an inlet end of said drum, means metering a plurality of dry materials onto said belt for transport to said drum, a spray nozzle directed axially into said drum at an outlet end thereof and connected through a fiow regulator to a liquid supply, an eductor connected to the outlet end of said drum for delivering mixed material therefrom, a main air system including a pressure regulating valve connected to said eductor for ejecting mixed materials therefrom and adapted for connection to a regulated source of high pressure air, an auxiliary air system connected to saidmain system on the supply side of the regulator valve therein and having a control valve opening same to the atmosphere, a pressure responsive rheostat connected in circuit with said feed motor, and means connecting said auxiliary air line to said pressure responsive rheostat and to said liquid flow regulator for controlling operation of same and to said main system regulating valve for controlling air pressure to said eductor whereby mixing and delivery is controlled by said control valve, and said auxiliary air system connecting means cutting off said feed motor and liquid flow regulator at a different pressure than the cutoff of air to said ejector whereby said drum is emptied each time mixing is stopped.

3. Mixing and delivery apparatus comprising in combination a material feed means, a mixing means, means metering a plurality of dry material onto said material feed means for transport to said mixing means, a liquid means for delivering liquids to said mixing means and connected through a controllable liquid flow means to a liquid supply, an eductor positioned to receive materials from said mixing means and adapted for connection to a source of air under pressure for entraining mixed materials to expel same therefrom, a flexible conduit having one end fastened to said eductor,'a placing gun connected to the other end of said flexible conduit for controlling the placement of mixed material forced therefrom, a main air system including a pressure regulating valve connected to a regulated source of high pressure air and to said eductor, a manually operable pressure control means associated with said placing gun and comprising an auxiliary air system connected to said main air system on the supply side of the pressure regulating valve therein, said control means being operable to open said auxiliary air system to the atmosphere, a pressure responsive device connected in circuit with said material feed means, and means connecting said manually operable control means to said pressure responsive device and to said liquid flow means for differentially controlling the operation of said device and said flow means and to said regulating valve for controlling air pressure to said eductor whereby mixing and delivering is automatically controlled by said manually operable pressure control means.

4. In a mixing and delivery apparatus having a cylindrical drum rotated at high speed about the longitudinal axis thereof by a motor, continuous feed means driven by a motor and providing a continuous controllable supply of proportioned materials to said drum for mixing therein, fixed scraping means extending into said drum in scraping relation thereto for tumbling materials therein for intimate mixing, and, an eductor means for delivering mixed materials from said drum in combination with a controllable spray means for spraying a liquid in a controlled flow counter-currently to the travel of materials through said drum, control means comprising a main air system to said eductor for entraining mixed material therein and delivering same from the eductor, a controllable means for controlling the amount of air to said eductor, an auxiliary air pressure system of variable pressure connected to said main air system on the supply side of said controllable means and including a control valve for controlling the control means, a pressure responsive device connected in circuit with the motor driving said feed means and connected to said auxiliary air system for control therefrom, and a liquid regulator valve connected to said spray means and to said auxiliary air system for control by the latter whereby said control valve in the auxiliary air system controls the amount of material fed to said drum and liquid sprayed therein as well as the delivery of material from said drum, said control valve being located at the terminal point of said auxiliary air system and beyond the points where said pressure responsive device, said liquid flow means, and said controllable means connect into said auxiliary air system.

References Cited in the file of this patent UNITED STATES PATENTS 416,950 Ransome Dec. 10, 1889 888,766 Stocker May 26, 1908 998,762 Faller July 25, 1911 1,070,798 Green Aug. 19, 1913 1,372,385 Wilson Mar. 22, 1921 2,072,886 Hollis Mar. 9, 1937 2,298,016 Lincoln Oct. 6, 1942 2,583,742 Lepin et al Jan. 29, 1952 2,623,737 McEachran Dec. 30, 1952 FOREIGN PATENTS 161,741 Great Britain Apr. 21, 1921 737,246 France Oct. 3, 1932 

